Typical power converters for performing power conversion between a direct-current (DC) voltage and an alternating-current (AC) voltage include a pair of upper- and lower-arm switching elements connected in series to each other for each phase of the AC voltage. Such a power converter alternately turns on the upper-arm switching element and the lower-arm switching element to perform power conversion between a DC voltage and an AC voltage.
On-off switching operations of a switching element of such a power converter may yield the occurrence of a surge and/or power loss. For addressing the occurrence of a surge and/or power loss, a technology has been proposed; the technology variably sets the rate of changing, i.e. switching, a switching element from one of an on state and an off state to the other thereof according to a value of at least one parameter. As the at least one parameter, a DC voltage input to the power converter can be used.
Japanese Patent Application Publication No. 2011-10441, referred to as patent document 1, discloses a driving device for a switching element as an example of the technology.
The driving device disclosed in the patent document 1 includes a plurality of current paths connected to the on-off control terminal of a switching element; the current paths respectively include resistors having different resistance values from each other. The driving device also includes a plurality of path switching elements provided on the respective current paths. Selectively turning on one of the path switching elements selects one of the current paths to be connected to the on-off control terminal of the switching element. This changes the value of a drive current flowing to or from the on-off control terminal of the switching element through the selected one of the current paths in comparison to the value of the drive current through another of the current paths. This varies the rate of switching the switching element from one of the on state and the off state to the other thereof.